Two Landscape Questions: Supersymmetry and M-theory

[Curious6]

Just two questions that come to mind when thinking about the string landscape proposed by Susskind and others:

1. When talking about the string landscape, do people refer to the supersymmetric string vacua or the non-supersymmetric string vacua? Is it only the supersymmetric string vacua whose number is estimated to be 10^100?

2. Are all the string vacua different solutions to one theory (M-theory for example) or do they all represent different theories just related by dualities and no underlying grand theory?

Thanks to anyone who is willing to answer any of these points.

 

[marcus]

this may help for starters:

Mike Douglas just posted this:
Basic results in Vacuum Statistics
http://arxiv.org/abs/hep-th/0409207

Peter Woit's comment on Douglas paper appeared shortly afterwards:
http://www.math.columbia.edu/~woit/blog/archives/000082.html

Douglas is AFAIK the world's chief authority on the statistics of string vacua
and he talks about both SUSY and non-SUSY in his paper.

Peter Woit's comment is helpful because he boils down to a few words the overall conclusion that he gets from Douglas paper, which is a survey and kind of a "status report" on the string vacua business. However you have to check Woit's comment against the original and not automatically take it at face value.

 

[Curious6]

Interesting some of the comments made by Douglas, but is he then saying that string theory now DOESN'T predict supersymmetry? I thought one of the basic pillars on which this theory was constructed was supersymmetry! I'm sorry if it sounds stupid, but I don't really understand all these papers yet (I've just graduated from high school) and was wondering what it would mean for the finding of superpartners at the LHC?

 

[marcus]

... and was wondering what it would mean for the finding of superpartners at the LHC?

apparently theorists have been waffling about what to expect.
It is really a test of theory.
A theory should make unequivocal predictions so that the experiment can either agree or disagree with theory. this one of the main reasons you bother doing experiments

but if theorists will not sign off on a prediction before the experiment is run, then the chance to test something is lost.

I can't tell for sure if Douglas is betting on SUSY or no-SUSY at LHC energies. If we follow Woit's reading of Douglas paper then Douglas (a prominent string theorist) is betting on no-SUSY.

If you find this unsatisfactory all I can do is sympathise.
I offer the Douglas link only because it is the most recent authoritative string word on this that I know of (not because it will set anyone's mind at rest)

 

[selfAdjoint]

Interesting some of the comments made by Douglas, but is he then saying that string theory now DOESN'T predict supersymmetry? I thought one of the basic pillars on which this theory was constructed was supersymmetry! I'm sorry if it sounds stupid, but I don't really understand all these papers yet (I've just graduated from high school) and was wondering what it would mean for the finding of superpartners at the LHC?

Correct me if I'm wrong, but I believe some people are looking toward getting much that is in the superstring theories to be represented in bosonic (non-supersymmetric) string theory, via new discoveries about the supporting math. Sorry, I don't have any links for this. It's just an impression I got from reading things here and there.